1. Field of the Invention
This invention relates to the repair of damaged pipe joints, and in particular to a portable apparatus for refacing of drill pipe section joints and the like on site.
2. General Background
The invention will be described with reference to the refacing of drill pipe section joints, but it will be understood that its application extends to the refacing of any type of pipe sections and any type of joints, such as for example, metal flanges.
Drill pipe sections have to be removed and refaced in the course of drilling operations due to the fact that abrasive fluids, often under high pressures, cause considerable wear and damage to the pipe section joints. Also, the frictional contact during make-ups and additions to the drill string is a contributing factor in causing damage to the joint and, in particular, to the joint shoulders. Since damaged joints will leak, whole sections have to be removed and refaced to ensure that all pipe sections in the string have even joints and mate properly.
For years, the conventional method of refacing a drill pipe joint was to send the damaged pipe section to a machine shop to be reworked by means of a lathe and, often, rethreaded at the same time. Since this was a time consuming operation and since very often no rethreading was necessary, portable refacing machines were developed in more recent years which are easier to transport to the rig site and which are specifically designed to do the refacing job. Descriptions of some of these portable machines which have been patented are listed in the following table: